It is perhaps possible to imagine also that a company of men might have been forced accidentally to sea in some large canoe from the coast of Africa, or on the other side from some of the islands of the Pacific, and so driven across the intervening water, and landed upon the American shores. It is true that it would be exceedingly improbable that any such combination of circumstances would occur as could lead to such a result. The canoe or boat must have been very large, the stock of provisions very great, and the wind, while it must not have been violent enough to engulf the boat, must still have blown very long. and very steadily to have carried a company of men so far before they all perished of hunger and thirst. All this would have been very improbable. Still it would be difficult to show that it could not occur. From the hundreds and perhaps thousands of boats full of savages that have been blown off to sea from the coasts of Africa, or from the South Sea Islands, it would be impossible to prove positively that there could never have been one that by any chance could have reached the American shores.

There is still another mode by which we can imagine the animal and vegetable life of America to have been communicated to it from other regions, and that is, by supposing that there was in former ages some direct connection between the two continents by a tract of land which has since become submerged. It is well known now that the crust of the earth is not in a stable condition. It is subject to changes and movements of various kinds, which are now going forward all the time, and have probably always been going forward. In some places the land is slowly rising; in others it is slowly subsiding. There are many places in the world where towns and cities which formerly stood high and dry on the land are now under water. The land has slowly subsided, so that the sea at the present time flows over it, and people passing in boats now look down and see the old foundations, and fragments of the fallen walls and columns, at the bottom.